Comment posting isn't working on my blog

My WordPress instance is at esr.ibiblio.org.

I was able to ship a new post a few hours ago, but commenting (on any post) fails with an indefinite hang.

My blog’s access to the Akismet spam checker is also failing.

I’ve taken the liberty of updating your blog from 5.4.1 to 5.5.1, and I also updated akismet. If you’re okay with it, I could also use wp-cli to add a user in order to test things from within the web-based wp-admin interface, but I have stopped short of doing that. Please let us know whether that would be okay, and also whether the updates resolved your issue.

I see the update. Thanks - I was planning to do that once I could run a backup of my content.

Comment posting is half-working. It reports a 504 failure, gateway timeout, but then the comment eventually gets through. I’m guessing your mysql server is being laggy under load.

I also can’t get a backup. mysqldump is no longer on my path on the login machine. Attempting backup remotely with

mysqldump --opt -Q -h mysql2.ibiblio.org -u esrblog

yields this message:

mysqldump: [Warning] Using a password on the command line interface can be insecure.
mysqldump: Got error: 2003: Can’t connect to MySQL server on ‘mysql2.ibiblio.org’ (110) when trying to connect

I believe my response in the other thread you started here is relevant.